At the end of the movie when the mob guys come to the boat house to move the body, Barry the Blade shoots a raccoon with his gun which has a silencer. But, later when Reggie shoots the neighbor's alarm system with Barry's gun, it does not sound like it has a silencer anymore.
In the movie, Reggie comments on Mark's Led Zepplin t-shirt, saying they were a great band. Mark accuses her of being one of those adults who pretends to like cool bands to get close to little punks like him. This parallels an incident where Brad Renfro was reading for the role of Mark, and a suit in the production office saw his Megadeath t-shirt and claimed to like that band, too. Renfro said the same thing to the producer that Mark eventually says to Reggie in the film.